Britain will build a new wing at Kirikiri Prison in the Nigerian city of Lagos so that it can transfer Nigerian prisoners there, the government in London has announced.

The new 112-bed wing, which will cost 700,000 pounds (973,000 dollars) and be compliant with UN standards, will make it easier for Britain to comply with a prisoner transfer agreement it signed with Nigeria in 2014.

Under that deal, eligible prisoners serving criminal sentences in Nigeria and Britain can be returned to complete their sentences in their respective countries.

The British government did not indicate how many prisoners might be moved or when the project is likely to be completed.

Nigerian prisons — many of them built by British colonisers more than 100 years ago — are severely overcrowded, leading to the spread of diseases.

The government in Abuja has said it is developing a strategy to tackle the issue.

Britain’s own prison system has been showing signs of severe strain in recent years, with overcrowding, rising suicide rates and a growing problem with drug trafficking and other crimes within jails that were sometimes built in the Victorian era.

Kirikiri is not one of the oldest prisons in Nigeria but it does date back to colonial times.

In February, the government said the prison in the southern city of Port Harcourt, which was originally designed to hold 800 prisoners, currently has nearly 5,000. It said 3,700 of them had been awaiting trial for more than five years.

In a written statement to parliament, British Foreign Secretary Boris Johnson said tenders had been placed and a supplier identified to conduct the building work at Kirikiri.

He did not name the supplier.

The project will be funded from Britain’s Conflict, Stability and Security Fund, which has an annual budget of more than one billion pounds and aims to commission projects that can help prevent conflicts and stabilise countries or regions.